By Monya Baker

Cancer drugs such as Herceptin are known as ‘personalized medicines’ because they are prescribed for subgroups of patients who share specific genetic traits. But truly individualized therapies are represented by treatments such as Provenge, which consists of patients’ own cells that have been extracted, exposed to an antigen that trains them to go after prostate cancer and re-infused.

The latter category is a tougher nut to crack, yet, ever since the US Food and Drug Administration (FDA) approved Provenge a year ago, cell-based personalized medicine has continued to garner interest. A course of three infusions of the treatment costs $93,000, but demand is still high. Earlier this year, Dendreon, the Seattle-based company that makes Provenge, announced it had received FDA approval to expand the number of production facilities for the product from 12 to 48.

Optimists are quick to cite Provenge as the crest of a wave of new therapies. “It has huge implications,” says Ronald Levy, a co-founder of Idec Pharmaceuticals (which merged to form Biogen Idec in 2003). “There may be 50 other therapies who hope to follow in the Provenge example.”

Although Levy, who is now at the Stanford University School of Medicine in California, is buoyant about the future of personalized cell-based therapies, he learned the hard way that some forms of personalized medicine prove too cumbersome to scale up. In the 1980s, he began creating antibodies designed for individual patients with lymphoma. Levy and his colleagues would identify telltale receptors on the wayward lymphocytes for each patient and then produce personalized antibodies designed to attack only his or her cancerous cells. Some 50 patients were treated with antibodies made this way, says Levy. “It worked most of the time, but it became economically unfeasible.” So he and his Idec colleagues instead developed the blockbuster rituximab, an antibody that targets a protein found on all B cells, allowing many patients with lymphoma to receive the same drug.

Bill Rastetter, a former chief executive at Idec and now a partner at Venrock, a venture-capital firm in Palo Alto, California, says efficacy as well as economics led him to decide against making individualized antibodies. Idec’s projected selling price for the personalized antibody approach was $50,000 per course of therapy, with about one in five patients showing remissions longer than those projected from chemotherapy alone. In contrast, about six out of ten patients benefitted from rituximab, he says, at a cost of about $10,000 per treatment course. (Levy notes that the approaches were never tested side by side, so efficacy is hard to compare.)

(Click here to continue reading.)

Image: Jim Dowdalls/Photo Researchers, Inc.